Gear drive for dial mechanisms



May s, 1951iL N. E. KLEIN GEAR DRIVE FOR DIAL MECHANISMS Filed OC'b. 31, 1945 INVENTo. /VOr/va/v E, K/@m BY ATTORNEY Patented May 1951 GEAR DRIVE FOR DIAL MECHANISMS Norman E. Klein, Clemson, S. C., assigner to the United States of America as represented by the Secretary of the Navy Application October 31, 1945, Serial No. 625,887

(-Cl. 'i4-10.8)

4 Claims.

This invention pertains to the art of dials and nds particular application in a device for operating dials such as are employed in radios and like apparatus.

The invention comprises a drive embodying a gear train. The gear train of the disclosed embodiment comprises directly intermeshing gears, but it is to be understood that the scope of the invention encompasses gearing and gear trains in the broader sense of these terms, including such equivalents as sprockets, pulleys, sheaves, etc.

The gear train of the invention comprises a gear and a pinion with parallel axes, and constituting the driving and driven members of the train. The gear is larger than the pinion, and specifically in the disclosed embodiment the gear diameter is several times greater than the diameter of the pinion. This provides a gear ratio with a predetermined limited angular displacement of the gear for each revolution of the pinion, the total angular displacement of the gear being less than a complete revolution thereof and coincident lwith a plurality of revolutions of the pinion.

Such a drive mechanism is particularly useful in radios, for a diminutive angular displacement of an electrical member to be made manually by a much larger rotation of a knob, for example. This enables precise and accurate manual control. The gear, for example, can be keyed to the rotor shaft of a variable condenser, and the knob attached to the pinion, to enable accurate tuning.

rlhe angular displacement of the gear is preferably limited to an amount less than a complete revolution, to indicate the angular displacement of the electrical device under control, the device being limited by itsdesign to an arc of rotation less than a complete revolution. Pursuant to this pur-pose, stops are provided in the device of the present invention, the stops respectively being carried by the gear and the pinion, and being rotatable in a common plane on intersecting paths. The stop of the gear is positioned radially to rotate on a smaller circle than the gear diameter. The stop of the pinion is positioned radially to describe a circle that intersects the circle of rotation of the gear. The stops are positioned circumferentially of their respective circles of rotation to abut at one or the other or both intersections between circles, abutting engagement of the stops operating to hold the driving and driven elements against further rotation.

It will be understood that, excepting in the case of the circles of rotation intersecting at a point, they will intersect at two points on each of the described circles, and that these points will dene arcs of intersection in both circles.

, In the practice of the invention of the disclosed embodiment, at least one of the stops is extended radially of the circle it denes to span both arcs, and by means of this construction the stops will abut wherever they happen to meet in the intersecting arcs.

Manual rotation of a knob, such as a radio dial knob, into abutting engagement of a pair of stops, may be sufficiently7 severe to dislocate adjustment of the electrical apparatus, or otherwise injure the equipment. To avoid this danger the device of the invention embodies a structure that operates to absorb the shock of the stops meeting in abutting engagement. Accordingly, a resilient connection is provided between the knob and the pinion.

Principles of the present invention, and the structure and operation of the disclosed practical embodiment thereof, will be better understood from the accompanying drawings.. In the drawings- Fig. 1 is a front view of a radio dial embodying the invention,

Fig. 2 is a cross-sectional elevation taken on line 2--2 of Fig. 1, and

Fig. 3 is a front elevation of the mechanism of Fig. 1, with parts removed to illustrate operation thereof.

The dial mechanism is mounted on a base I0, which may conveniently constitute the panel of a radio. The housing II is provided for the dial mechanism, and is attached to the panel, for example by the screws I2. In the case of the invention being embodied in a radio, the shaft I4 carries some electrical device thereof. By Way of illustration, the shaft I4 could carry the rotor of a variable condenser, used for tuning the radio. The bearing I6 is provided for the shaft I4, the bearing being attached to the panel I0 by suitable means such as the nuts I8.

The shaft I4 carries a gear, in the embodiment shown the gear being of the composite type 20, 22. The gear 2B is fixed to the hub 24, which is keyed to the shaft I4 by means of the set screw 25. The teeth of gears 20 and 22 coincide, and the gear 22 is urged to rotate relative to gear 20 under action of the spring 26. Spring 26 operates to hold the teeth of composite gear 20, 22 in snug meshing engagement -with the companion pinion 32 to eliminate backlash. The antibacklash device embodying the spring 26 is not claimed as part of the present invention.

The pinion 32 is journaled in the bearing 44, that is screw threaded into the housing H and fixed thereto byrmeans of the set screw 48. The 5 knob 38 is attached to the shaft 34, in a manner to be described more fully hereinafter, the knob 38 being attachedto thebe'ar-ing bushing ,42 to which the dial plate 48 is attached. Rotation of the knob 38 operates to rotate the dial plate i0 4! and the pinion 32 in unison, theV pinion in turn driving the gear 28, 22. The dial plate 4811i may include the peripheral indicia shown, and the indicating plate 58 may be provided-fixed toI the housing Il and positioned to indicate `the 15- angular position of the dial plate 48.

It will be noted that the gear 28; 2 2 iis se'veraltfA ends of the strand 35 are projected into diametrically opposite sockets in the cap 31, that is attimes the diameter of the pinion 32 in the emrbodiment shown, and that each rotation oijthe pinion 32 produces a limited predetermined angu- 20 lar displacement'of y'the Agear-2li, V22. It will alsoV be noted that a predetermined fraction of a complete revolutionof the gear 20, "22 is coincidentY with a plurality Vof revolutions ofthe pinion 312.

The gear22'is providedrwith indicia 28, Fig. l3, 25 whichv travel past the aperture -38 in the housing`v il, andl thus are'successivelyplacedr in View of Y the observer by rotation Yof Athe knob 38; `Itis desired that the gear 22 be able `to rotate through an arc that will enable all of the indicia to passv 30 into View through themaperture, butV that the gear 22 be prevented from moving those portions of its face in view through Vthe aperture38 that` are beyondthe range of indicia-23. Stops 54 and 52 are provided, and these operatefto limit the 35 v factured and used-by or iorftheGovernmentof .S f. Ythe United Statesof America for'governmentalr.

purposes without thelpayment of` any,v royalties Y thereon-0r therefor.

arc ofrotation of thel gear 22- to the fraction of acomplete revolution that is determined bythe range of the indicia 28:"

The stop 54 is providedattached to thegear 25, 22 by being projected from thepfaceof the 40 hub 24, and4 it describes a circle that is smaller than the diameter of gear 28, 22. Attached to' the pinion 32 to rotate therewithl is the stop 52 companion to the stopf54. -The stopr52projects v Y from the rear face of the dial 48, and is positioned 5 Y' to rotate in a -plane common to the plane orrotation of the stop 54. The stop 54 describes` the circle 55, and the stop 52 describesthe circle v5l' that intersects the circle 55 at pointsf58`and 53;y

For each rotation of. the-pinion 32,7the stop 52y 5o intersects the circle 55 at points 58 and 53. During coincident rotations of the gear 20, 22 while the stop 54 is locatedvinthe larger arc of the circle 55 between the points 58:.and- 59, the stops 54 and 52 do not meet, andthe stop 52`.does not -55 interfere with rotation of the gear 2li, 22. But. when the pin 54 passesthe :point 58 in its counter-clockwise rotationyor point 53 in its clock-' A Y wise rotation, the stops 54 and 52 `will meet and abut against each other arresting the gear 28,- so' 22 and preventing its continued rotation- A. gear ratio between the pinion 32 and gear. 28, 22 canl be providedwtolcause thestops 52,54 to meet; precisely at the point 58 during counter-clockwise rotation of the gear 28, 22, andthe point 58 65 during clockwise ,rotation fof the gear 28, 22. This may be undesirable in some cases, and isnot essential for practice of the invention.

In the practical application of the principlesj of the invention disclosed, the stop 52is extended 70 radially of its circle 5l for'it to span the inter-` seating. arcs of circles 55 andv 5l ,between the. points 58 `and '59. Accordingly,'during' its counter-clockwise rotation, the `,stop 54 will!` abut againstthe 'stop 52 wherever they 'meet after it '75 into abuttingengagement.

The bushing 42, thatcarries the dial 48 andthe knob 38 integral therewith, is mounted to rotate -on thebearing sleeve 44 in which the shaft 34 `'of pinion; l32vis journaled. The resilient strand 35 provides a shock absorbing connection betweentheshaft 34;andfthef knob 38. The resilient strand '3 5. is, projectedgdiametrically through the shaft 34, a's 'shown in Fig. 2, the strand 35 being projectedjbeyondiithesuriace oi the shaft. The

tached to the knob 38 in xedengagement therevvwith bymeans of the screws 35.--.The sockets of. the cap 3lthat -receive the endstof the strand.35 e.:

are spaced-away f-romthefsurface of the shaft 34 of the principles of the invention, which .however -is not limited to the specific embodiment disclosed. The scope of the inventionisdeterininedz, by the accompanying claims.V 1

The invention described-herein maybe manul Y Y What is claimed is 1. A gear .train comprising afpinion' and a gear of greater diameter rotatable on parallellaxes, the l -pinion :and geareach comprising. a stop attached `to rotate withitythe severalstopsbeing positioned;` to rotate in a common plane, the stop oli-the gear being positioned@ radially '-to'rotate. `on a smaller-circle than the gear diameter, -thevstop of thezopinion being positionediradially.to'rotate. on a circle that' intersects'the7 circle of; rotation ofthe sto'pof the gear, the stops being located circumif'erentially on their respective 'circles ofrotation -to abut atthe int'ersectionfbe;A tween circles, 'a'knob for rotating. 4the-driving member of the pinion and gear being 4.coaxial therewith and rotatable relative thereto; resilient means connecting-the knob andthe driving ineinf ,.-ber torotatelthe member by rotationof the knob.

2. A gear'ltrain comprising 'a pinion and agear: :z of greater diameter rotatable. on 'parallelaxes'thel pinion and. gear each comprising'a-stop :attached to rotate `withit, the several stopsbeing positioned. :to rotate ina commonplanathe stop ofthe gear .being positioned radially 'to' -rotate `onr a smaller circle than the'ge'ar diameterfthe stopl of the pinionbeing positioned radially to rotateV on a circle thatiintersectsxthe `circle of rotationof the stop of'the gear, the stops being locatedcircumferentially on their respective circles of rotation lto abut at the .intersection between circles, 'a shaft carrying. the, ndriving member of thepinion .and

gear, a knob for rotatingthe driving member be- Ying mounted rotatable ori-the Vaxis of thes'haft; a resilient strand projected diametrically throughv the shaft and extending beyond the surface thereof, the ends of'thestrand projecting into diametrically opposite sockets in the knob, the sockets being positioned radially away from the surface of the shaft.

3. A gear train comprising a pinion and a gear of greater diameter rotatable on parallel axes, the pinion and gear each comprising a stop attached to rotate with it, the several stops being positioned to rotate in a common plane, the stop of the gear being positioned radially to rotate on a smaller circle than the gear diameter, the stop of the pinion being positioned radially to rotate on a circle that intersects the circle of rotation of the stop of the gear, the stops being located circumferentially on their respective circles of rotation to abut at the intersection between circles, a shaft carrying the driving member: of the pinion and gear, a knob for rotating the driving member being mounted rotatable on the axis of the shaft, a wire projected diametrically through the shaft and extending beyond the surface thereof, the ends of the wire projecting into diametrically opposite sockets in the knob, the sockets being positioned radially away from the surface of the shaft.

4. Operating mechanism for a radio dial of the like comprising a pinion and a gear rotatable on parallel axes, the gear ratio between the pinion and the gear providing predetermined angular displacement of the gear for each complete revolution of the pinion and total angular displacement of the gear less than a complete revolution thereof for a plurality of revolutions of the pinion, stops limiting rotation of the gear to the extent of the total angular displacement thereof,

the stops being rotatable in a common plane and 35 being attached to rotate with the pinion and the gear respectively, the stop of the gear being positioned radially to rotate on a smaller circle than the gear diameter, the stop of the pinion being positioned radially to rotate on a circle that intersects the circle of rotation of the stop of the gear, and extending radially to span the intersecting arcs, indicia on the gear indicating its angular displacement.

NORMAN E. KLEIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 985,221 Spear Feb. 28, 1911 1,203,840 Bailey Nov. 7, 1916 1,477,785 Szukalski Dec. 18, 1923 1,618,525 Franklin Feb.` 22, 1927 1,729,046 Lovejoy Sept. 24, 1929 1,791,641 Schroder Feb.` 10, 1931 1,913,288 Pierce June 6, 1933 2,086,035 Johnson July 6, 1937 2,213,492 Galter Sept. 3, 1940 2,294,280 Carrington Aug. 25, 1942 2,349,118 Simpson May 16, 1944 FOREIGN PATENTS Number Country Date 105,013 Austria July 15, 1926 503,776 Germany July 17, 1930 511,187 France Dec. 18, 1920 

